In gas turbine engines, compressed air discharged from a compressor section and fuel introduced from a source of fuel are mixed together and burned in a combustion section. The mixture is directed through a turbine section, where the mixture expands to provide rotation of a turbine rotor. The turbine rotor may be linked to an electric generator, wherein the rotation of the turbine rotor can be used to produce electricity in the generator.
The combustion section of a typical gas turbine engine may include a fuel injector assembly that distributes fuel into the compressed air stream before the stream reaches main and pilot fuel injectors of a combustion chamber in a process referred to as pre-mixing. The pre-mixing process provides a high degree of flexibility during engine tuning and is an important component for engine emissions and dynamics.
One type of prior art fuel injector assembly comprises a ring-type fuel injector assembly including a fuel ring, a fuel supply tube, and attachment legs for attaching the assembly to a portal or flow sleeve of the combustion section of the engine. Fuel is delivered from a source of fuel to the fuel supply tube, which conveys the fuel to the fuel ring. The fuel is delivered into the air stream through an annular array of apertures that are formed in a radially inward surface of the fuel ring. Such a prior art fuel injector assembly is disclosed in U.S. Pat. No. 7,249,461, the entire disclosure of which is hereby incorporated by reference.
Common problems associated with prior art fuel injector assemblies include inadequate structural integrity and the delivery of fuel too closely to a liner assembly of the combustion section. Inadequate structural integrity may lead to fuel leakage and decrease engine efficiency. Delivering the fuel too closely to the liner assembly can be problematic in that the fuel may auto-ignite near the liner surface and burn holes in the liner.
There is a continuing need to provide a fuel injector assembly that delivers an efficient amount of fuel into the air stream from the compressor section while having adequate structural integrity to prevent fuel leakage and which also reduces the risk of auto-igniting in the vicinity of the liner assembly.